Five people - three men and two women - were killed and six were injured in an explosion at a fireworks factory near Zaragoza in northeastern Spain, officials have confirmed.

Six people are being treated in local hospitals, with two in intensive care. The explosion, according to Aragon Radio took place at around 2.15pm local time. The cause of the explosion is not known, Reuters reported.

A spokeswoman for the regional government of Aragon confirmed the death toll and injuries, saying that firefighters were continuing their work at the factory, which exports products to other European countries and Canada.

Local media reported that the explosion took place at Pirotecnica Zaragozana's factory in the area, but the company's main office has not been able to immediately confirm this.

The Spain Report said that the Aragon regional government has declared a day of morning today (1 September).